1. Field of the Invention
The present invention relates to a lens-fitted photo film unit in which it is possible to select photographic modes with a single operation member. Particularly, the present invention relates to a lens-fitted photo film unit in which photographic errors to be caused by operational defect of an operation member are prevented from occurring.
2. Description of the Related Art
Various kinds of lens-fitted photo film units are sold. The lens-fitted photo film unit includes a photo film loaded at the time of manufacture thereof. In the former lens-fitted photo film unit, are fixed a stop, a shutter speed, a focal length and so forth. In this case, however, photographic conditions for taking a picture in a proper exposure are narrow. Thus, it is desired that the lens-fitted photo film unit has wide photographic conditions to take a picture of high image quality.
In consideration of the above desire, at present, are sold various kinds of the lens-fitted photo film units in which it is possible to change plural photographic modes by operating a single operation member. For instance, in these kinds of the lens-fitted photo film units, a larger stop is set at the time of flash photographing (Japanese Patent Laid-Open Publication No. 2000-305221), and plural photographic modes are provided to change a stop, a shutter speed and a flashlight amount (Japanese Patent Application No. 2002-151328).
In the lens-fitted photo film unit provided with the plural photographic modes, the operation member is generally urged to an initial position by a spring for the purposes of preventing a misuse of a user and securing positional accuracy of a mode-changing mechanism. For example, in the lens-fitted photo film unit described in the forgoing Publication No. 2000-305221, a toggle spring is put on a stop changing member to urge the associated operation member via the stop changing member.
However, since the toggle spring has a dead point, the operation member is sometimes stopped at a halfway position of switching when a user puts a finger on the operation member and foreign objects of the sand or the like enter the operation member. In case the operation member stops on the way, the stop changing member also stops on the way to switching. Thus, an appropriate stop is not obtained and photographic image quality deteriorates. Moreover, if the stop changing member stops in a state that an aperture does not exist at a photographic optical axis, it is likely to happen that nothing is photographed.
It is a primary object of the present invention to provide a lens-fitted photo film unit in which positional accuracy of an operation member is prevented from affecting a function of an exposure changing unit.
In order to achieve the above and other objects, the lens-fitted photo film unit according to the present invention comprises a plurality of exposure adjusting means, an operating means, and an urging means. Each of the exposure adjusting means changes over between a large-exposure state and a small-exposure state. The operating means moves between a first position and a second position in association with the exposure adjusting means, and is disconnected from the exposure adjusting means while the operating means is moved to a third position beyond the second position. When the operating means is kept in the first position, the exposure adjusting means is set to the large-exposure state. When the operating means is kept in the second position, the exposure adjusting means is set to the small-exposure state. The urging means urges the exposure adjusting means toward the small-exposure state.
As to a stop changing member included in the exposure adjusting means, timing thereof for interlocking with an operating means is adapted to be late in comparison with the other of the exposure adjusting means. Further, switching of the stop changing member is completed early in comparison with the other of the exposure adjusting means.
In the lens-fitted photo film unit according to the present invention, it is possible to reduce bad influence to be caused by operational defect of the operating means and to be applied to the respective exposure adjusting means. Thus, photographic errors may be prevented from occurring due to the operational defect of the operating means. As to the stop changing member which is likely to cause the photographic errors, the switching operation thereof is rapidly carried out in comparison with the other exposure adjusting means so that the bad influence is hardly drawn by the defective errors of the operating means.